Railroads (particularly high speed) need to be long and straight. What happens if people don't want a dozen trains roaring through their neighborhood every day? It's difficult to just go around it.

What happens if people don't want a railroad through their property at all? After all, once a railroad is sitting on your land, it's difficult to repurpose it for much else. The state can try eminent domain, but that takes time and lengthy court cases, and the costs add up quick.

The best routes already have railroads. Their right of ways are in private hands.

To put it in perspective, the only all season transcontinental route is the southern most line on the article’s map. It only exists by virtue of the Gadsden Purchase in 1854. The right of way is controlled by the corporate successors of the Southern Pacific.

The non-existence of viable alternative all season grades across the west is why the Gadsden Purchase happened. The US had assumed surely such routes existed in Alta California following its succession in 1848 via the treaty of Guadalupe Hidalgo.